Alan G. Glover, David J. Horsley, David V. Dorling TransCanada PipeLines Ltd. Calgary
Construction in summer 1994 of 33 km of NGT's Eastern Alberta system main line (48-in. OD; 12-mm W.T.) was the first North American long-distance, large-diameter pipeline to use Grade 550 steels. Here, a pipe crew lines up the next joint before performing the root pass with an internal welder. (Photograph from TCPL, Calgary)
Standard construction techniques are used for Grade-550 projects. Remaining weld passes are all made with external mechanized welding "bugs." The leap frog action of the various welding stations completes the hot pass, fill passes, and cap pass. (Photograp...